<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>ID选择器</title>
</head>
<style>
    #red {
        color: red;
    }
</style>
<body>
<!--id只能使用一次-->
<div id="red">
    迪丽热巴
</div>
</body>
</html>